I just got Stella4D and I'm trying to play around with it. It seems you covered pretty extensively 4D uniforms, but I had trouble trying to create non-uniforms. I wanted to make an Icosahedral pyramid, for example, so I tried using a J2 pentagonal pyramid as vertex figure to create it, but it only gave me part of the polytope with no way to close it. Is there another way to create this? I found some 4D .off files online of various interesting CRF polytopes but I don't know how to create those on my own. Any suggestions? Thanks.

Vertex figures only work for uniform polytopes, because it requires all vertices to be equivalent.

OFF files are in a simple text format, so you can look inside one and you'll be able to see how they work. But it's easiest to create them via code.

Stella4D has menu items to build a prism on the current polyhedron, but not a pyramid. I should probably add that, but I think I didn't because there's no obvious height to choose. Often it wouldn't be possible to keep the edges all the same length.

Building antiprisms would also be nice, but in 4D the top and bottom are duals of each other (actually they are in 3D too, but the dual of a regular polygon is the same regular polygon, rotated, so no one notices).

Actually the next major release will have a feature that would allow you to make an icosahedral prism, but this is still an unknown time away (unknown even to me!).

What about an ability to cut off pieces of uniform polyhedra? That would give rise to lots of interesting non-uniforms. Maybe create it by choosing a cross section to cut it at (this could really be a great feature for 3D also!).

I'm trying to work with .off files to create 4D non-uniforms, but it's way too tedious to try to figure out all the faces and cells that would connect the vertices. I found this program called qhull (www.qhull.org) that will calculate the convex hull and create an .off file from input vertices, but it only outputs the cell vertices, not the faces and not the cell by face like Stella4D requires. Do you have a program to enumerate the faces to create a file Stella can read? Thanks

I figured out the problem: I was using the wrong formula to calculate the vertices so the ones I had were creating coplanar faces so that's probably why it was crashing. Once I fixed the formula it worked no problems.

I'm making .stel files of all the segmetochora, I was wondering if there is any way to embed in a file the ability to ask for a prism number and create something from that prism/antiprism like in the n-gonal prism built-in file. Thanks